MySQL 8.0 Release Notes
MySQL 8.0 Source Code Documentation
If, for some reason, you wish to prevent users from seeing traces of their queries, start the server with the options shown here:
--maximum-optimizer-trace-max-mem-size=0 --optimizer-trace-max-mem-size=0
This sets the maximum size to 0 and prevents users from changing this limit, thus truncating all traces to 0 bytes.